A company named NeuroSky has developed brainwave reading technology that can detect when a person is focusing on a fixed image. They created a prototype toy lightsaber that lights up when the user concentrates on it. When his/her attention wanders, it turns off. Apparently this is just the beginning of what they can determine from reading brainwaves. The initial market will be toys and games, but I think it could be used in a wide range of applications.